JP2003183294A - Method for preparing glycol ester of carboxyethyl- methylphosphinic acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparing a carboxymethyl-methylphosphinic acid glycol ester starting from an elemental yellow phosphorus as a reaction component by eliminating defects of a conventional technique. <P>SOLUTION: This method for preparing the carboxymethyl-methylphosphinic acid glycol ester involves (a) reacting the elemental yellow phosphorus with methyl chloride in the presence of an alkali(ne earth) metal halide to afford a mixture containing alkali(ne earth) metal salts of methylphosphonous, phosphorous and phosphinic acids as mail components, (b) esterifying the methylphosphorous acid in the mixture obtained in the step (a), (c) removing the methylphosphorous acid from the mixture, (d) subjecting thus obtained methylphosphorous acid to the addition with an acrylate to afford a diester, (e) hydrolyzing the obtained diester to afford carboxymethyl-methylphosphinic acid, and (f) directly esterifying the carboxymethyl-methylphosphinic acid with ethylene glycol. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing carboxyethylmethylphosphinic acid glycol ester and uses of the product produced by this method.

[0002]

Carboxyethylmethylphosphinic acid glycol ester is a valuable synthetic component in the production of flame retardant polyester fibers. For example, German Patent Application Publication (A) 3,940,713 describes formula (I)

[0003]

[Chemical 1] A method for producing a flame-retardant synthetic fiber containing a group represented by in a polymer chain is disclosed. This type of flame retardant synthetic fiber is commercially available as Trevira CS. U.S. Pat. No. 5,399,428 and German Patent 2,529,731 disclose flame retardant linear polyesters by incorporating carboxyphosphinic acid.

Carboxyl group-containing phosphinic acids are obtained by reacting phosphonous acid dihalides (dihalophosphines) with activated olefin compounds, such as acrylic or methacrylic acid derivatives, followed by hydrolysis (Houben-Weyl, Volume 12/1, page 230; KK Kha
irullin, TI Sobchuk, AN Pudovik, Zh. Obshch.Kh
im. 37, 710 (1967)). Upon hydrolysis with an organic acid, a halide of the acid is produced as a by-product.

Carboxyethylmethylphosphinic acid glycol ester is prepared by reacting methyldichlorophosphine with acrylic acid as described in US Pat. No. 4,062,888, Hoechst AG (1977), followed by intermolecular reaction. It can be obtained by forming an acid anhydride and esterifying with ethylene glycol (see Reaction Scheme 1).

The above-mentioned methyldichlorophosphines are conventionally prepared by themselves from phosphorus trichloride and methyl chloride in the presence of aluminum chloride in a very expensive and inconvenient synthetic method (Houben-Weyl, No. 12 / (Vol. 1, p. 306). This reaction is a highly exothermic reaction and is difficult to control on an industrial scale. Furthermore, like some of the abovementioned raw materials, various by-products which are toxic and / or corrosive, that is to say totally undesirable, are produced.

Furthermore, phosphonous acid dihalides can be reacted with alkyl halides in the presence of aluminum chloride (Houben-Weyl, Vol. 12/1, p. 232).

Phosphinic acid esters can also be prepared from phosphonous dialkyl esters by the Michaelis-Arbuzov reaction. The phosphonous acid dialkyl ester is prepared from a phosphonous acid dihalide and a hydroxy compound.

German Patent Application Publication (A1) No. 2,54
No. 0,283 discloses producing a carboxyl group-containing organophosphorus compound by adding a phosphine to an α, β-unsaturated carboxylic acid in the presence of aqueous hydrochloric acid and then oxidizing the same. .

[0010]

[Chemical 2] Reaction Scheme Figure 1: Preparation of carboxyethylmethylphosphinic acid glycol ester (German Patent 4,062,88
No. 8 or DE 2,529,731) The phosphinic acid esters are obtained by adding phosphonous acid monoesters to 1-olefins in the presence of peroxide catalysts. However, the yield is only slight. In the presence of alkoxide as a catalyst,
The addition reaction of the phosphonous acid monoester to the activated double bond proceeds better. Suitable unsaturated compounds are α, β
-Unsaturated carboxylic acid esters or α, β-unsaturated carboxylic acid nitriles, α, β-unsaturated ketones and alkyl vinyl sulfones and vinyl acetate (Houben-Wey
l, Vol. 12/1, pp. 258-259).

The phosphonous acid monoesters themselves are prepared from phosphonous dihalides by reaction with alcohols or by hydrolysis and subsequent esterification.

It is therefore desirable to have a process for the preparation of carboxyethylmethylphosphinic acid glycol esters which can be carried out in a simple manner and which provides a single product in high yield. Such a method should obviously be superior to the conventional method in terms of environmental hygiene.

[0013]

The object of the present invention is therefore to avoid the abovementioned disadvantages and to provide a process for the preparation of carboxyethylmethylphosphinic acid glycol esters starting from elemental yellow phosphorus as a reaction component. is there.

[0014]

The object of the present invention is, in the method described at the beginning, a) reacting elemental yellow phosphorus with methyl chloride in the presence of an alkali metal or alkaline earth metal hydroxide to give a main component. Producing a mixture containing the alkali metal and / or alkaline earth metal salts of methylphosphonous acid, phosphorous acid and phosphinic acid, b) esterifying the methylphosphonous acid from the mixture obtained according to a), c) this Removing the methylphosphonous acid from the mixture, d) adding the methylphosphonous acid thus obtained to an acrylic ester, e) hydrolyzing the diester thus obtained, f) the resulting carboxyethylmethylphosphinic acid with ethylene glycol Direct esterification to give carboxyethylmethylphosphinic acid glycol ester And the above method.

The process of the invention has the advantage over the previously known processes that, for example, phosphonous dihalides are avoided from the raw material and that there is a favorable equilibrium in the product distribution.

The reaction of step a) is preferably carried out in a two-phase system of an aqueous solution of an alkali metal or alkaline earth metal hydroxide or a mixture thereof and an organic solvent.

The organic solvent used is preferably a linear or branched alkane, an alkyl-substituted aromatic solvent, a water-immiscible or only partially water-miscible alcohol or ether, respectively, or It is contained as a combination of them.

It is further advantageous that the organic solvent used is toluene alone or a combination of toluene and alcohol.

The reaction (step a) is preferably carried out in the presence of a phase transfer catalyst.

The phase transfer catalyst is tetraalkylphosphonium-halide, triphenylalkylphosphonium-
Preference is given to halides or tetraorganoammonium halides.

The temperature in the course of the reaction of step a) is -20 to 20.
Advantageously in the range + 60 ° C.

More preferably, this temperature is within the range of 0 to 30 ° C.

The reaction of step a) is preferably carried out at a pressure in the range 0-10 bar.

In a preferred embodiment of the present invention, yellow phosphorus is suspended in a solvent or solvent mixture and then an alkyl halide and a formula MOH or M '(O
H) ₂ is reacted with compounds or mixtures thereof, where M is an alkali metal and M ′ is an alkaline earth metal.

Yellow phosphorus and methyl chloride are preferably 1: 1 to
They are reacted with one another in a molar ratio of 1: 3, whereby yellow phosphorus and the formula M
The molar ratio with the compound of OH or M '(OH) ₂ is 1: 1
˜1: 5.

In step b), methyl phosphonite is represented by the general formula R-OH, wherein R is a linear or branched alkyl group having 1 to 10 carbon atoms. ] The esterification is preferably carried out directly with a linear or branched alcohol of the formula It is further advantageous to use n-butanol, isobutanol or ethylhexanol.

In step c), the ester of phosphonous acid is preferably removed by distillation.

Esterification of the phosphonous acid to the corresponding monoester can be achieved with removal of the product water by azeotropic distillation, for example by reaction with an alcohol having a relatively high boiling point.

The addition in step d) is preferably carried out in the presence of a catalyst.

The catalyst in question is preferably a basic catalyst. In some cases it is also possible to use acids or cationic free radical initiators.

The basic catalyst is advantageously an alkali metal and / or alkaline earth metal alkoxide.

The acrylic ester of the general formula (II) is preferably an ester of the same alcohol used to esterify the methylphosphonous acid in step b).

The acrylic ester of the general formula (II) is preferably hydroxyethyl acrylate, methyl acrylate,
Ethyl acrylate, butyl acrylate or 2-ethylhexyl acrylate.

The invention also relates to the use of the functionalized phosphinic acid prepared by the process of the invention as a reactive flame retardant for polymers.

The present invention also relates to the use of carboxyethylmethylphosphinic acid glycol ester as a reactive flame retardant for thermoplastic polymers such as polyethylene terephthalate.

[0036]

[Chemical 3] Reaction scheme Figure 2: Reaction scheme of the method of the present invention for producing glycol carboxyethylmethylphosphinate.

[0037]

The invention is illustrated by the following examples: Example 1: Reaction of yellow phosphorus with methyl chloride

[0038]

[Chemical 4] A solution prepared by dissolving 26.1 g (0.05 mol) of tributylhexadecylphosphonium bromide in 1000 mL of toluene was introduced into a 5 L stainless steel pressure-resistant reactor, and 6
Preheat to 0 ° C. After the addition of 62 g (2 mol) of yellow phosphorus, the mixture is cooled to -10 ° C. with vigorous stirring, 202 g
Methyl chloride (4 mol) is then condensed. Then 40
0 g of 50% strength aqueous sodium hydroxide solution are metered in over a period of 2 hours while maintaining the temperature at -10 ° C. 400 g of water are added over a further hour, then the mixture is stirred for a further hour, warmed to room temperature and then the reactor is decompressed via combustion. Two homogeneous liquid phases are obtained. These are separated and analyzed.

The aqueous phase (weight: 920 g) contained 65.6 mol% methylphosphonous acid, 14.9 mol% phosphorous acid, 1
Containing 3.7 mol% phosphinic acid and 2.8 mol% dimethylphosphinic acid in the form of its sodium salt and 3
Containing mol% dimethyldiphosphine.

Phosphine oxidation / NaCl removal: 60 g of this solution in 5% strength hydrogen peroxide solution, 240 g of 36%
Mix with concentrated hydrochloric acid and 400 g of 2-ethylhexanol. After removing the water contained by distillation in a water separator,
The precipitated sodium chloride is filtered off and 100 g of 2-
Wash with ethylhexanol.

Example 2: Esterification of methanephosphonous acid in the reaction mixture:

[0042]

[Chemical 5] The ethylhexanol solutions of Example 1 are combined and heated in a water separator at slightly reduced pressure to about 120 ° C. for 6 hours.

Separation of the ester: The esterification reaction mixture is then freed from excess ethylhexanol by distillation and subjected to vacuum distillation. 0.3 mm pressure and 75 ° C
220 g of 2-ethylhexyl methanephosphonous acid are distilled off at the top temperature of. The product is obtained in the form of a colorless transparent liquid with a purity higher than 99%. This corresponds to a yield of 58% based on the yellow phosphorus used. Analysis: 16.0%
Phosphorus (theoretical value: 16.2%); ³¹ P-NMR: 34 pp
Doublet at m (pair of diastereomers).

Example 3: Addition of n-butyl methanephosphonate to butyl acrylate 136 g (1 mol) in a 500 mL five-necked flask equipped with a thermometer, reflux condenser, high speed stirrer and dropping funnel.
Of n-butyl methanephosphonate and 128 g (1 mol) of butyl acrylate are introduced. 5 mL of sodium butyrate (30% strength) is added dropwise to the stirred mixture at a rate that guarantees a reaction temperature of up to 120 ° C. The mixture is then reacted for a further 10 minutes at 80 ° C. A pale yellow liquid is obtained.

³¹ P-NMR (CHCl ₃ ): 56 ppm The dibutyl ester thus obtained was stored at 130 ° C. and 0.5
Distill under a vacuum of mm.

Example 4 Hydrolysis of dibutyl carboxyethylmethylphosphinate In a 1 L five-necked flask equipped with a thermometer, a reflux condenser, a high speed stirrer and a dropping funnel, 528 g (2 mol) obtained according to Example 3 were obtained. Introducing dibutyl carboxyethylmethyl phosphinate). 500 mL of water at 160 ° C was metered in over 4 hours and butanol / water-
The mixture is distilled off. 281 g of butanol are obtained, which corresponds to 95% of theory. The distilled off butanol is reused to esterify the methyl phosphonite. 300 g of carboxyethylmethylphosphinic acid are obtained as a white solid with a melting point of about 95 ° C. and a ³¹ P-NMR purity of> 97%.

Example 5: Esterification of carboxyethylmethylphosphinic acid with ethylene glycol 445.8 g of carboxyethylmethylphosphinic acid (2.93 mol) obtained according to Example 4 are 356.4.
Dissolve in 90 g of ethylene glycol (5.86 mol). A clear solution is obtained which is stable on storage.

Water produced during the esterification process is removed at 160 ° C. in a 1 L three-necked flask equipped with a thermometer, still head, distillation column and high speed stirrer.
The 54 g of distillate obtained after 2 hours is 100% water. The amount of water corresponds to the formation of 52.4% of theory of the diester. The phosphorus content of the product is 12.4% and contains no ethylene glycol. The color number (Hasen) is 30, and Berger (Berg)
er) Whiteness is 75%, yellowness is 5%, saponification degree is 420 mg (KOH) / g and water content (Karl Fischer titration) is 0.1%.

The product thus obtained can be used to produce flame-retardant polyesters.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Heinz-Peter Broyer             Federal Republic of Germany, Huert, Doctor             -Curten-Strasse, 3 (72) Inventor Elisabeth Jung             Germany, Bedburg, Garten             Strasse, 22 F-term (reference) 4H028 AA24 AA34 BA06                 4H050 AA02 AA03 AB80 AC40 AC70                       BA02 BA32 BA65 BB11 BB14                       BB15 BC10 BC11 BE10 BE11                       WA15 WA26

Claims (19)

[Claims] 1. A method for producing carboxyethylmethylphosphinic acid glycol ester, which comprises: a) reacting elemental yellow phosphorus with methyl chloride in the presence of an alkali metal or alkaline earth metal hydroxide to give phosphonite as a main component. Producing a mixture containing alkali metal and / or alkaline earth metal salts of methyl acid, phosphorous acid and phosphinic acid, b) esterifying the methyl phosphonite from the mixture obtained by a), c) from this mixture Excluding the methyl phosphonite, d) adding the methyl phosphonite thus obtained to an acrylic ester, e) hydrolyzing the diester thus obtained, f) the resulting carboxyethylmethylphosphinic acid directly with ethylene glycol Esterified to carboxyethylmethylphosphinic acid group Wherein the obtaining a call ester, the method described above. 2. The reaction is carried out in an organic solvent.
The method described in. 3. The organic solvent used is a linear or branched alkane, an alkyl-substituted aromatic solvent, a water-immiscible or only partially water-miscible alcohol or ether, respectively, or The method according to claim 1 or 2, which is contained as a combination thereof. 4. The process according to claim 1, wherein the organic solvent used is toluene alone or in combination with alcohol. 5. The method according to claim 1, wherein the reaction is carried out in the presence of a phase transfer catalyst. 6. The method according to claim 5, wherein the phase transfer catalyst is a tetraalkylphosphonium-halide, a triphenylalkylphosphonium-halide or a tetraorganoammonium-halide. 7. The method according to claim 1, wherein the reaction temperature is in the range of −20 to + 60 ° C. 8. The method according to claim 1, wherein the temperature is in the range of 0 to 30 ° C. 9. The process according to claim 1, wherein the reaction is carried out at a pressure in the range of 0-10 bar. 10. Yellow phosphorus is suspended in a solvent or solvent mixture and then reacted with an alkyl halide and a compound of the formula MOH or M ′ (OH) ₂ or mixtures thereof, where M is an alkali metal. And the method according to any one of claims 1 to 9, wherein M'is an alkaline earth metal. 11. Yellow phosphorus and methyl chloride are added in a ratio of 1: 1 to 1: 1.
They are reacted with one another in a molar ratio of 3, in which case yellow phosphorus and formula MOH
Alternatively, the method according to any one of claims 1 to 10, wherein the molar ratio with M ′ (OH) ₂ is within the range of 1: 1 to 1: 5. 12. The process according to claim 1, wherein in step b) methyl phosphonite is esterified in a mixture with an alcohol. 13. The method according to claim 1, wherein the phosphonous acid methane ester is removed by distillation in step c). 14. The process according to claim 1, wherein the addition in step d) is carried out in the presence of a catalyst. 15. The method according to claim 14, wherein the catalyst used is a basic catalyst. 16. The basic catalyst used is an alkali metal-
And / or an alkaline earth metal alkoxide. 17. The method according to claim 1, wherein the acrylate ester is methyl acrylate, butyl acrylate or ethylhexyl acrylate. 18. A method of using the carboxyethylmethylphosphinic acid glycol ester produced by the method according to any one of claims 1 to 17 as a reactive flame retardant for a polymer. 19. A reactive polymer for the preparation of a thermoplastic polymer such as polyethylene terephthalate, polybutylene terephthalate or polyamide with carboxyethylmethyl phosphinic acid glycol ester prepared by the method according to claim 1. Method used as a combustor.